Furnaces

ABSTRACT

A feed chute for charging a metal melting furnace includes a member which is movable to vary the effective cross section of the chute, the rate of passage of feed material through the chute being controlled by movement of said member.

United States Patent Ashdown et al. 14 1 June 27, 1972 1 FURNACES 2,072,392 3/1937 West et al. ..214/1s v [72] Inventors: Ne clmord Ashdnwn; Eugene Realm 2,343,337 3/1944 Somes ..266/33 R Ground. both of Tasmania Australia 2,829,184 4/1958 Khek ..13/33 2,962,!74 1ll1960 Shekels... ....2l4/l8 SC [73) Assignee: Electrolytic Zinc Company oi Australasia 3,266,644 8/1966 lpsen 4 ..2l4/l8 R Llmlled, Melbourne. ri A r lia 3,425,676 2/1969 Shekels "266 33 R [22] Filed: June 16, 1970 [2]] Appl. No; 46,742 Primary ExaminerGerald A. Dost AttorneyCushman, Darby & Cushman [30] Foreign Application Priority Data 9 June 19, l 69 Australla 56667169 ABSTRACT [52] US. Cl. .266/33 R, 2|4/l 8 R A f d h m f r char i a metal melting furnace includes a {5 l Int. Cl ..F27b 9/38 member hi h i able to vary the effective cross section of [58] Field 0| Search..................2l4/l8 R. 188C, is V, 35 R; h chute, h rate of passage of feed material through the 266/27- 33 33 S; 13/33 chute being controlled by movement ofsaid member.

[56] Relerences Clted UNITED STATES PATENTS 3,344,939 10/1967 Shekels ..214/1a sc 4 Claims. 3 Drawlns Figures WWW-"TNT? Z rvnmcas This invention relates to improvements in or relating to metal-melting furnaces, and more particularly to improvements in or relating to means whereby metal is charged to such furnaces.

Commonly metal-melting furnaces of the type used, for instance, for melting zinc sheets prior to ingot casting in the conventional electrolytic process for the production of zinc include a feed chute for charging the metal to the bath of the furnace. Such feed chutes normally consist of a length of metal ducting of rectangular cross-section which passes through the shell of the furnace to a position some distance above the level of molten metal in the furnace. The chutes are sometimes flared at the lower end. A column of feed material is normally maintained in the feed chute so that metal is continuously charged to the bath of the furnace. The base of the column of sheet metal feed material rests on the floor of the furnace, and, as the lower sheets melt, the column of sheet metal feed material descends into the furnace.

However, with such an arrangement considerable difficulty has been encountered in devising suitable means for controlling the rate of entry of the metal charge into the furnace in order to cope with interruptions to the withdrawal of molten metal from the furnace.

According to the present invention there is provided a feed chute suitable for charging a metal-melting fumace, characterized in that said chute includes a member which is movable to vary the effective cross-section of the chute, the movement of said member being governed by control means so as to enable the rate of passage of feed material through the chute to be controlled.

It will be understood that by, for example, continually arresting and re-starting the descent of the column of feed material a very close control can be kept on the rate of entry of metal charge into the bath of the furnace.

ln the case of a feed chute of substantially rectangular crosssection, the said movable member may suitably comprise a hinged lower section of one of the walls of the chute, arranged such that the hinged section moves freely between the two adjacent walls so as to vary the effective cross-section of the chute and thereby control the rate of entry of the feed material into the furnace. In this circumstance the two walls of the chute adjacent to the movable member may also be flared to allow the movable wall section or flap, an appropriate degree of outward movement while maintaining the enclosure provided by the chute. In this way the effective cross-section of the chute may also be enlarged so as to free any feed material jammed in the chute. A suitable amount of flare may be 4 to 6.

The movement of the hinged flap may suitably be governed by control means comprising an air ram or similar device with associated control equipment, the said control means being situated essentially outside the furnace shell. in this embodiment the push rod of the ram passes through an opening in the furnace wall and is connected to the hinged flap by a clevis pin and hook or similar arrangement to permit easy removal of all parts from outside the furnace.

The air ram or similar device should be capable of being operated such as to allow rapid application and release of pressure to the column of feed material so as to closely control its descent through the chute.

The feed chute and its attachments may be fabricated from materials well known to those skilled in the art.

The invention is hereinafter described, merely by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a sectional elevation of a feed chute in accordance with the invention installed in a conventional furnace,

FIG. IA is a cross-section A-A ofFlG. 1,

FIG. 2 is a diagrammatic drawing showing a means of controlling the air ram.

A conventional electric induction metal-melting furnace l of the type normally employed in the zinc industry is provided with a feed chute 2 shown containing a zinc sheet feed, the said feed chute being of substantially conventional dimensions, but being provided at its lower end with a hinged flap 3. The said flap 3 is hinged at a point outside the furnace and is capable of being opened and closed by means of a push rod 4 attached to the flap by a clevis pin and hook device 5. The walls of the chute adjacent to the flap are flared to an angle of about 5 to allow the flap a suitable degree of outward movement to enlarge the effective cross-section of the chute.

The push rod 4 passes through an opening in the wall of the furnace and is connected to a double-acting air cylinder 6. The air supply to the double-acting air cylinder 6 is provided via a double-acting solenoid valve 7.

The solenoid valve 7 delivers air to one or other side of the piston of the cylinder 6, depending on the operation of the control switch 8, such that the hinged flap 3 is made to open or close.

The control switch 8 is spring-loaded so that in its normal position it causes the hinged flap to close. An isolating switch 9 de-energizes the solenoid valve 7 and renders the springloaded control switch 8 inoperative. The hinged flap remains in the open or closed position depending on its position prior to opening the isolating switch 9. The extent of opening of the flap 3 is determined by the adjustment of the capstan nut 10.

During normal melting operations the push rod 4 is fully retracted to the extent permitted by the adjustment of the capstan nut 10 and the hinged flap 3 is open.

Whenever there is an interruption to the withdrawal of molten metal from the furnace the hinged flap is closed simply by closing the isolating switch 9. The push rod is thrust into the furnace, closing the hinged flap and thereby arresting the entry of feed material into the furnace. A wedge may be inserted behind the push rod as a safety measure in the event of a failure of the air supply.

When it is desired to recommence entry of feed to the furnace the operator momentarily opens the hinged flap 3 by operating the spring-loaded control switch 8 against its return spring and then causes the hinged flap 3 to close again quickly by releasing the spring-loaded control switch 8.

When the hinged flap 3 is momentarily opened the zinc sheets begin to slip downwards into the furnace and when the hinged flap 3 is subsequently closed again the downward movement of the zinc sheets is arrested.

The operation is continually repeated until the bottom of the column of zinc sheet feed contained in the chute is safely resting on the floor of the furnace.

The operator then holds down the spring-loaded control switch 8 against its return spring until the flap is fully open to the extent permitted by the adjustment of the capstan nut 10 and subsequently opens off the isolating switch 9.

We claim:

1. A chute for the controlled feeding of loose metal sheets to a melting furnace comprising a substantially vertical feed chute of rectangular cross-section extending with its lower end into the melting furnace and including a movable member, said movable member comprising a lower section of one wall of the chute pivoted by its top edge to the feed chute so as to allow the said movable member to pivot into and out of the feed chute so as to vary the effective cross-section of the chute and to clamp the column of sheet metal feed against the op posite wall of the chute, said movable member being of substantially greater length than the width of the feed chute and said movable member being provided with control means for alternately and momentarily clamping and releasing the sheet metal feed material contained in the chute, thereby momentarily arresting and freeing the downward travel of the column of loose metal sheets and providing a means for controlling the rate of feed of the metal sheets into the furnace.

2. A chute as in claim 1 wherein said pivoted wall section is arranged to remain within the walls of the chute at all times.

3. A chute as in claim 2 wherein said pivoted wall section is pivoted to said one wall at a point outside the furnace.

4. A chute as in claim 1 wherein the two walls adjacent said one wall are flamed at their lower ends so as to accomodate an outward movement of said pivoted wall section while maintaining the enclosure provided by the chute.

: e e e e 5 

1. A chute for the controlled feeding of loose metal sheets to a melting furnace comprisinG a substantially vertical feed chute of rectangular cross-section extending with its lower end into the melting furnace and including a movable member, said movable member comprising a lower section of one wall of the chute pivoted by its top edge to the feed chute so as to allow the said movable member to pivot into and out of the feed chute so as to vary the effective cross-section of the chute and to clamp the column of sheet metal feed against the opposite wall of the chute, said movable member being of substantially greater length than the width of the feed chute and said movable member being provided with control means for alternately and momentarily clamping and releasing the sheet metal feed material contained in the chute, thereby momentarily arresting and freeing the downward travel of the column of loose metal sheets and providing a means for controlling the rate of feed of the metal sheets into the furnace.
 2. A chute as in claim 1 wherein said pivoted wall section is arranged to remain within the walls of the chute at all times.
 3. A chute as in claim 2 wherein said pivoted wall section is pivoted to said one wall at a point outside the furnace.
 4. A chute as in claim 1 wherein the two walls adjacent said one wall are flared at their lower ends so as to accomodate an outward movement of said pivoted wall section while maintaining the enclosure provided by the chute. 